The present invention relates generally to an alphanumeric control keyboard with depressible keys for electric or electronic machines, of the type comprising a plurality of keys which are mounted through the apertures of the keyboard and are urged by return means to their initial position in which the keys protrude from the apparent or external face of the keyboard. The invention also relates to the electric or electronic machines equipped with such a keyboard.
Keyboards of this type are well-known at the present time and used in all kinds of machines such as computer control desks or consoles, typewriters, hand-held or pocket calculators, all machines that include depressible-key control means.
Various problems arise when mounting and using such keyboards. Indeed, the keys are usually returned to their off or inactive position by springs or equivalent elastic return means which suffer from a certain number of important drawbacks due to the fatigue phenomenon which appears in the return spring (loss of stiffness, marked settling or breakage), the sensitivity to corrosion, the technical and climatic surrounding, the difficulty of mounting each key associated with an independent return spring, the high manufacturing costs, and so forth.
Moreover, the various keyboard elements must be assembled by the machine manufacturer owing to the close mechanical association of the control keys with, on the one hand, the corresponding contact elements of the electric or electronic circuits of the machines and, on the other hand, with their mechanical return means.
The invention has precisely for its object the avoidance of such drawbacks of the known control keyboards.
The invention also has for its purpose a control keyboard which can be made with its keys independently of the machine for which it is intended and which can thereafter be simply mounted on the machine.